1. Field of the Invention
The present invention relates generally to pre-mix beverage dispensing valves and more particularly to solenoid operated beverage dispensing valves.
2. Background
Pre-mix beverage dispensing valves are well known in the art, and serve to dispense carbonated drinks such as soda pop and beer. These valves are designed to dispense a carbonated drink with a minimum of carbonation loss, to the atmosphere and by minimizing foaming. This result is accomplished primarily with a compensator positioned upstream of the valve seat that helps to reduce the pressure on the pre-mix, generally 50 to 80 pounds per square inch, to that of atmosphere. Prior art pre-mix valves have typically been manually operated wherein a lever is pulled toward the operator to dispense a drink. A spring provides for assisting in moving the valve back to the closed position and maintaining the valve closed and seated.
Various attempts have been made at making a pre-mix valve electrically operable, such as through the use of a solenoid. However, the initial force needed to overcome the pressure on the pre-mix beverage, as well as that of the shaft spring, has presented problems. An electrically operated valve is seen in U.S. Pat. No. 4,708,155 wherein a leveraged solenoid system utilizing a spring linkage is used to reduce the size and power consumption of the solenoid. However, further improvements involving lessening of the initial force required to open a pre-mix valve are required to insure long term reliable operation.
The present invention comprises a solenoid operated pre-mix beverage dispensing valve having low opening force requirements. The valve includes a valve body having an actuating shaft slideably mounted along a central axis thereof. The shaft includes a first contact end extending outward of a front end of the valve, and a second end positioned within the valve body. A spring is positioned around the shaft first end and between a spring retainer and the valve body. The valve body includes a radiussed circular seat surface tapering to a smooth cylindrical surface area. A quad-ring is retained in an annular grove extending around the actuating shaft and provides fluid tight sealing between the actuating shaft and the cylindrical surface area of the valve body. The actuating shaft also includes four stop tabs extending radially and equidistantly from and around a common perimeter of the actuating shaft. In the closed position of the valve the four tabs are in contact with the radiussed surface of the valve body and the quad ring is in sealing relationship with the cylindrical valve body surface.
A compensator housing is secured to an attachment end of the valve body and a compensator is positioned within the housing. The compensator includes a cylindrical bore for sealably receiving the second end of the actuating shaft. A further quad ring extending around the second end of the actuating shaft provides for fluid tight sealing between the second end and the compensator bore. An air pressure equalization channel extends axially through the center of the actuating shaft and provides air communication between the compensator bore and a transverse channel in the valve body. The transverse channel provides air communication to ambient air pressure.
A frame is secured to the exterior of the valve body and the frame structure provides for pivotal mounting thereto of a first lever arm. A second lever arm is pivotally secured to the frame and has a first end positioned between the first lever and the contact end of the actuating shaft. A solenoid is secured to a top surface of the valve body and includes an armature having an external end thereof for engaging with the first end of the first lever arm. A cup contact lever is pivotally suspended below the valve body and is operable to actuate a switch for energizing and de-energizing the solenoid.
In operation, the cup lever is moved to operate the switch, which then energizes the solenoid. The armature is then drawn into the solenoid thereby operating the first lever. The first lever then contacts the second lever which, in turn, moves against the contact end of the actuating shaft. The actuating shaft is made to then move against the biasing force of the spring and move the first quad-ring out of contact with the valve cylindrical surface and the four stop tabs out of contact with the radiussed surface. As a result thereof, beverage is permitted to flow between the actuating shaft and the valve body to the dispense nozzle.
Those of skill will recognize that the valve of the present invention uses a compound lever system to gain a mechanical advantage for substantially lessening the force required to initiate dispensing. In addition, the air pressure equalization system is improved over the prior art to further lessen the initial force required to open the valve. As a result of the lessened opening force, a lower power solenoid can be used resulting in a substantial increase in the reliability and longevity of the valve.